1. Field of the Invention
This invention relates to the positioning of robotic arm members and other devices, for measuring and monitoring selected parameters of forces acting on the arm members or devices, and is directed more particularly to an assembly which effects movement of such members and/or devices in accordance with preestablished computer programs and in accordance with real-time inputs by a human operator.
2. Description of the Prior Art
Movable measurement probes are widely used in research facilities to measure parameters such as pressure, temperature, and flow angle of a moving liquid or gas. Extensive data is gathered from readings taken from the measurement probes. By moving a probe, a large area of a flow stream can be surveyed and monitored without introducing a large bulky measurement probe or a large number of small individual probes, either of which can itself affect the flow parameters, and therefore the measurements.
Motion control systems currently in use typically are cumbersome, difficult to use, slow to take data, difficult to set up and troubleshoot, and quite expensive. Validation of numerical tools used for the design and analysis of turbomachinery requires increasingly more detailed surveys of flowpaths. The demand for such data has dictated additional requirements for probe activation systems found in testing facilities.
In U.S. Pat. No. 3,890,552 (hereinafter "'552"), issued Jun. 17, 1975, in the names of George C. Devol et al, there is disclosed a computer programmed controller for controlling two axes of motion, or two robotic arms. In the '552 controller, first and second manipulators cooperate with each other in executing a series of operations, including motions in a substantially mirror-image mode. Each manipulator has a main operating structure that carries a work head through several degrees of freedom in space, and the work head itself is capable of various secondary movements. The two manipulators are capable of operating under separate controls for executing related but independent operations. Separate manual controls are used for the two manipulators which can be provided with memory capabilities; the manipulators can also operate automatically under the separate control of their respective memories. The two manipulators are operable in a cooperative, complementary mode, with the same commands being used directly or indirectly to control both manipulators. In the case of indirect control of the second manipulator, control commands are used to control operation of the first manipulator, and control input for effecting corresponding, cooperative operation of the second manipulator is derived from the operations of the first manipulator, the two manipulators operating in a corresponding manner and maintaining their work heads in alignment with each other. In the case of direct control, the second manipulator responds to the same control commands as those supplied to the first manipulator, the two manipulators executing the same motions or mirror-image motions as required, adjustment being introduced for maintaining alignment and control of the work heads.
Thus, in '552 a controller controls a primary manipulator, and a secondary manipulator follows the primary. Alternatively, the secondary manipulator is provided with an independent motion capability. Both manipulators operate according to a set of pre-defined motion commands, and both continuously monitor and adjust positions of the manipulators.
It appears that the '552 system is not field-programmable, inasmuch as most controls are hardware-based. It further appears that changes to profiles, or parameters, of manipulator movement are entered into the system by punch cards or text file (data set), and could not easily be changed. The '552 patent does not appear to teach or suggest a system which permits changing a motion profile in real time. In short, '552 does not provide an easy to use, field-programmable motion system.
In U.S. Pat. No. 5,224,032 (hereinafter "'032"), issued Jun. 29, 1993, in the names of Heinz Worn et al, there is disclosed a process and system for controlling movements of robotic arms on a program-controlled machine. The system includes a position control unit, a velocity control unit, and a power control unit. Loads acting on an arm during operation of the machine are measured by sensors. Load signals are fed back regeneratively in the sense of an increase in the position control variance, to a summation point of the position and/or velocity control unit. To increase or decrease mechanical flexibility of the arm, a controllable amplifying or attenuating device is provided. The sensors are types selected in accordance with the loads to be measured and preferably are directly associated with axes of the arm.
Thus, in the '032 patent there is provided means for controlling an arm on a program-controlled machine, with the help of sensors. The '032 system incorporates mechanical flexibility into the arm movements, which flexibility can be advantageous in view of obstacles otherwise in the motion path, or load changes. Again, it does not appear that the '032 system is easily re-programmed or changed in real time.
In U.S. Pat. No. 5,784,542 (hereinafter "'542"), issued Jul. 21, 1998, in the names of Timothy Ohm et al, there is disclosed a teleoperated robot system for use in microsurgery. The system includes a low friction, low inertia, six-axis force feedback input device comprising an arm with double-jointed, tendon-driven revolute joints, a decoupled tendon-drive wrist, and a base with encoders and motors. The input device functions as a master robot manipulator of a microsurgical teleoperated robot system including a slave robot manipulator coupled to an amplifier chassis which is coupled to a workstation with a graphical user interface. The amplifier chassis is further coupled to the motors of the master robot manipulator, and the control chassis is coupled to the encoders of the master robot manipulator. A force feedback is applied to the input device and is generated from the slave robot to enable a user to operate the master robot via the input device without physically viewing the slave robot. Alternatively, the force feedback can be generated from the workstation to represent fictitious forces to constrain the input device control of the slave robot to be within predetermined boundaries.
Thus, the '542 patent presents a robot system in which a user operates a master robot via an input device, such as a graphical user interface, without actually viewing the slave robot. The slave robot is controlled by the motion of a master robot. It appears that the '542 system lacks the ability to move arms according to a set of motion commands that can be changed in real time.
Accordingly, while the prior art noted above has provided significant and substantial steps forward in the state of the art, there remains a need for an assembly for moving a robotic device along selected axes, which assembly is versatile, user-friendly, and subject to field re-programming and to changes by a user in device movement parameters in real time, by use of a point-and click user interface. Furthermore, the prior art does not fulfill the need for a control system that is able to move axes along pre-programmed paths or motion profiles, autonomously in automatic nulling mode, and/or interactively.